As it is well known in this technical field, the pressure filters of the above mentioned type mainly perform the function of mechanically filtering the water, by removing the impurities such as the suspended material, the particulate and the filth particles. Normally this function is performed by a series of sponges, realized with expanded plastic material with communicating cells, preferably with polyurethane.
For taking care of the cleaning of the filtering elements without having to resort to the opening of the filter, technical solutions have been developed for long intended to compress the filtering sponges, so as to free them partially or totally from the particulate material entrapped therein.
In other technical fields, for cleaning the exposed surface of the filtering elements the use of brushing elements has been for long spread. These latter act substantially as a racla, which is guided in a sliding way with a to-and-from movement along the exposed surface of the filtering body.
Although advantageous under several aspects, known filters, which use sponges with open cells as filtering elements, have a still unsolved drawback.
The drawback stays in that, in spite of the use of the brushing elements, progressive volume variations and dimension reductions of the filtering element can be noted in time with an unavoidable worsening of the brushing element efficiency and increase of the load loss due to the obstruction.
In consideration of the drawback detailed above, an aim of the present invention is that of devising a pressure filter having such structural and functional characteristics as to ensure a high brushing element efficiency although occurring a progressive volume reduction of the filtering element.
A further aim of the invention is that of providing a pressure filter wherein the brushing element has high maneuverability and manoeuvre flexibility when cleaning the filtering element.